Bootmii has started going to a black screen when choose HB channel...

Check the compatibility list for SD & SDHC cards for HBC and Twilight Hack

 

some random thoughts:

HBC works fine when not launched from bootmii?
Did you reinstall HBC? or only did part of the hackmii installer like only choose to setup SD ?
Did you update or install another HBC manually ? a wad maybe?
there's an open source version of HBC, and it's using a new TitleID (OHBC) instead of the previous one (LULZ).
Bootmii needs to know the HBC's titleID to launch it, and it doesn't know OHBC.


Can you boot system menu from bootmii without black screen?
do you have bootmii.ini file on SD ? check if it's set to proper video mode.

 

Tried all this no good. Last thing I did was install Priiloader to load usb loader on boot. As always I fix 1 thing and break another. I originally installed bootmii using hackmii installer v1.2. Should I try and install bootmii or hbc again using that? I can load hbc fine tho via Priiloader

 

Why are you posting the same problem in different thread? it's hard to follow and help you.
You are also bumping many old threads with no reason.

Bootmii is triggered before priiloader !
priiloader is never reach if you set Bootmii to boot HBC, therefore you can't expect Priiloader to boot your loader.

I'm not sure what you expect your console to do, but mixing guides without understanding what you are doing, what's it's changing on your console and how each of these installed apps are doing is not a good idea.